There are a number of cases where the flow of fluids between two or more medical appliances has to be controlled. This fluid flow generally has to take place in a sterile environment so as to avoid the risk of infection, especially where the transfer of fluids into and out of a living body is involved. Difficulties are often encountered in connecting such appliances together to allow fluid transfer between them in a safe and hygienic manner.
Examples of situations in which medical appliances need to be connected together in this way include the administration of blood transfusions, intravenous delivery of drugs and nutrients, administration of anaesthetics and, more particularly, techniques involving dialysis. The latter usually involves infusion of fluids into, and draining of waste fluids from, the human body; in recent years, a large number of medical treatments have been developed which rely on such techniques. The usual method of infusing and draining the fluid is via a catheter implanted in the patient's body.
One example of such a treatment is "continuous ambulatory peritoneal dialysis" (CAPD), typically used on patients having kidney disorders. According to this treatment method, a relatively large amount of a specially formulated fluid is infused into the patient's peritoneum, from a sterile fluid bag, via a catheter implanted in the patient's abdomen. This fluid is retained in the peritoneum for a number of hours, usually between 6 and 12, and then drained from the body into an empty bag, again via the catheter, and immediately replaced by fresh fluid.
CAPD is a very effective form of treatment, allowing the patient to carry on a nearly normal life. However, patients undergoing CAPD are very susceptible to infection, which can give rise to peritonitis and frequently require hospitalisation. It is believed that the main source of infection to these patients is from airborne bacteria entering the catheter during the above described fluid bag exchange procedure.
In order to reduce the incidence of infection during the exchange of fluids in such treatment methods, various designs of connection system have been developed for connecting together the appliances involved (ie, in the case of CAPD, the catheter, the new fluid bag and the empty fluid bag). One known connection system comprises a bag of fresh fluid, coupled by means of a Y-piece connection to an empty fluid bag. Using this connector, the patient is required to open the catheter at least once on connection to the Y-coupler and once on disconnection, thus exposing the catheter to airborne bacteria. An alternative, more sophisticated, connection system comprises a coupling device which joins a new fluid bag and an empty bag and which opens a catheter automatically on connection thereto and closes it on disconnection. Such a device is relatively expensive to produce and not always simple to use.
None of the presently available connection systems is totally satisfactory in overcoming the problem of infection, and most suffer from other drawbacks such as lack of ease of use, comfort of wearing and/or reliability. There is therefore still a need for a connection system to control the flow of fluids between medical appliances, which system is not only safe to use (ie, avoiding the risk of infection and leakage) but also simple and convenient, so as to avoid the risk of incorrect usage by a patient or medical practitioner. It is therefore an aim of the present invention to provide a device for connecting together two or more medical appliances, which overcomes or at least mitigates the above described problems encountered in use of conventional connection devices.